Since the door glass windows are used regularly, they have a great influence on the vehicle owner's perception of vehicle quality. Today's customers demand that moveable door window glass operates smoothly. Experimental methods have been developed to evaluate window glass smoothness and positional stability. This paper presents experimental results that quantify the chattering and positional stability of the window glass. For window glass smooth operation and tracking, the measurements were taken on glass chatter, glass velocity, motor current, motor voltage, and glass stall force. The change in glass position was measured on the vehicle during several stages of four poster durability testing to evaluate window glass positional stability during road induced vibrations. Using these experimental methods, the designers should be able to evaluate several window glass functional requirements and achieve cost/time savings.